Counting Atoms, Naming, and Bonding

So…this is chemistry.

Classification of Elements

• Uses position on the periodic chart (dictated by how the element acts) to tell what the element “is”–We already did this with the coloring of

the chart

Valence electrons

• The number of electrons in the outermost shell

• Tells a bit about how it will react• Can tell by position on the periodic chart

Counting Atoms

• So two elements combined makes a compound. There is bonding involved.

• You need to COUNT the number of each type of atom in a compound

• You can tell this from the formula

Some more examples

Magnesium fluoride (MgF₂)• One atom of

Magnesium• Two atoms of

Fluorine

Sodium chloride (NaCl)• One atom of

Sodium• One atom of

Chlorine

You can name compounds based on what they are made of

• Mono - 1• Di - 2• Tri - 3• Tetra - 4• Penta - 5

• Hexa - 6• Hepta - 7• Octa - 8• Nona - 9• Deca - 10

Some examples…

• Nitrogen oxide• Dinitrogen oxide• Nitrogen dioxide• Dinitrogen

pentoxide• Dinitrogen trioxide

So let’s try counting a few…

•H₂O•LiF•K₂S

•H2SO4

•CH4

•C8H10N4O2

Another complication…

•2 K₂S•3 H₂O•4 H₂SO₄

Yet another wrench…

•3 Ca(NO3)2

•2 Fe(NO3)2

•5 BaSO4